Magnetic deflection coils and yokes



Jan. 14, 1964 J. MARLEY 3,118,092

MAGNETIC DEFLECTION coILs AND YoKEs original Filed Jan. 11, 195e s sheets-sheet 1 Jan. 14, 1964 J. MARLEY MAGNETIC DEFLECTION COILS AND YOKES 3 Sheets-Sheet 2 Original Filed Jan. 11, 1956 FIG.3

Jan. 14, 1964 J. MARLEY MAGNETIC DEFLECTON COILS AND YOKES 3 Sheets-Sheet 3 Original Filed Jan. 11, 1956 FIGA United States Patent MAGNETIC DEFLECTIN CILS AND YKES John Marley, West Caldwell, N.J. assigner to Hazeltine Research, Inc., Chicago, Ill., a corporation of Illinois Original application lan. l1, 1956, Ser. No. 558,526.

Divided and this application June 13, 1960, Ser. No.

5 Claims. (Cl. 317-200) This invention relates to coils and, more particularly, to magnetic deflection coils and deflection yokes. Such yokes are utilized to deflect beams of electrons or similar electrical particles and are particularly useful in connection with cathode-ray tubes and the like.

This application is a division of application Serial No. 558,526, filed January ill, 1956, now abandoned, and entitled Method of Manufacturing Magnetic Deflection Coils and Yokes.

Considering the case of a cathode-ray tube in more detail, it is conventional practice to place a plurality of deflection coils adjacent the neck portion of such cathoderay tube in order to deflect the electron beam developed by such tube. Such deflection coils are frequently combined in an overlapping manner to form a complete deflection yoke. In operation, the coils of the yoke are energized by suitable electrical currents thereby causing the coils to develop magnetic deflection fields which, in turn,

erve to deflect the electron beam thereby causing such beam to scan a display surface in a desired scanning pattern.

In order to obtain accurate control over the deflection of the electron beam, it is desirable to utilize deflection coils wherein the coil turns are accurately positioned relative to one another in a known manner. Also, in order to reduce manufacturing costs, it is desired that there should be a high degree of consistency between the operating characteristics of deflection coils of the same construction. This, again, requires that the coil turns be accurately positioned, otherwise manual adjustment of the coil turns may be necessary after the coil is formed in order to obtain deflection coils having the same operating characteristics. This desired accuracy of coil turn positioning could be readily achieved if some method were available for utilizing printed wiring techniques.

lIn order to develop magnetic deflection fields having a high degree of linearity, it is frequently necessary to utilize coils in which the turns are distributed in a nonuniform manner, that is, that the density of coil turns vary from one end of the coil to the other in a precise but nonuniform manner. Such nonuniformity of coil turn density compensates for other nonuniformities that would otherwise be present and thereby enables a uniform or undistorted deflection field to be produced. `It would be desirable to have a method of coil manufacture which would readily enable such results to be obtained with a minimum of effort.

It is further desirable that a deflection yoke made up of a plurality of deflection coils be as compact as possible. This leads to increased power efficiency and decreased distributed capacitance in the yoke because the yoke structure then has a minimum of unused air spaces between the various coils. Also, the defocusing effects normally produced by the end turns of the coils are reduced because the end turns of adjacent windings are positioned more closely to one another thereby better enabling the end turn fields developed by one to cancel the end turn fields developed by the other.

It is an object of the invention, therefore, to provide new and improved deflection coils and yokes :which achieve one or more of the foregoing advantages.

It isa further object of the invention to provide new ananas Patented Jan. 14, 1964 "ice and improved deflection coils having increased precision of coil turn positioning.

It is another object of the invention to provide new and improved deflection coils which readily lend themselves to printed circuit techniques.

It is a further object of the invention to provide new and improved deflection coils having a desired nonuniform density of coil turns.

It is an additional object of the invention to provide new and improved deflection yokes having reduced end turn effect, reduced distributed capacitance, and increased power efficiency.

In accordance 'with the present invention, there is made possible a ladder coil capable of being rolled into a coil suitable for use in a cathode-ray tube deflection yoke.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, the scope of the invention being pointed out in the appended claims.

Referring to the drawings:

FIG. l is a plan View of a ladder coil constructed in accordance with the present invention;

FIG. 2 is a plan view of an alternative form of ladder coil;

FIG. 3 is a perspective view of a pair of such ladder coils after undergoing further operations in accordance with this invention;

FIG. 4 is a side elevational View showing a complete deflection yoke constructed in accordance with the present invention;

FIG. 5 is a cross-sectional view taken on the section line A-A of FIG. 4, and

FIG. 6 is a symbolic electrical circuit diagram for explaining the operation of the FIG. 4 deflection yoke.

Referring to FIG. l of the drawings, there is shown one form of ladder coil for making magnetic deflection coils in `accordance with the present invention. For the purposes of this specification the term ladder coil is defined as an electrical coil having the following characteristics:

h l) All conductors are physically arranged in a rollable s eet.

(2) Each individual lturn is generally in the form of a rectangle.

(3) The complete coil resembles a common ladder in form with the turns forming two side pieces and at least three rung sections.

(4) Individual turns encircle one or more of the windows of the ladder form.

(5) The complete coil is capable of being rolled up into a spiral roll.

Also, a rolled ladder coil is defined as a ladder coil which has been rolled up so that the side pieces of the ladder coil roll into two distinct cylindrical coils and all rung sections overlay each other and form one compact group interconnecting the cylindrical coils (as will be explained in more detail).

The ladder coil 10` illustrated has turns which progress continuously between the inner region represented, for example, by the terminal lil and the outer region of the coil represented, for example, by the terminal 12. In other words, the coil is made up of one continuous conductor, for example wire, Iwhich progresses in a continuous manner from the terminal ll to the terminal l2. VAs indicated in FIG. 1, the turns of this coil lil are arranged so that the coil has a first end lila and a pair of elongated sides lllb and lille (which may be considered the side pieces of the ladder form) which are intermittently bridged by segments of a fraction of the total turns so that the width oi the side pieces may vary in a progressive manner from one end of the coil to the other. The turn segments which intermittently bridge the two elongated sides lldb and lila are represented by the groups Mld-Milz, inclusive, which, together with group ldu, may be considered Ithe rung sections of the ladder form. The effect of thus intermittently bridging some of the turns is that the total number of turns carried by one of the side pieces, for example the side lllb, continuously decreases from one end of the coil to the other. This, in turn, enables the width or" the side piece to decrease in a like manner. This decrease in width is indicated by the successive dimensions lVl, W2 and W3 which, as appear in the drawings, may be caused to successively decrease by displacing each turn following a rung segment toward the inner region of the coil so as to maintain a substantially equal spacing of all turns from that region.

The coil lll may be affixed to a sheet of flexible dielectric material l`3 which, preferably, has a number of windows cut therein. The windows are rectangular areas where the dielectric material has been removed and are indicated by the areas llt-i8, inclusive.

The open areas of the coil between the rung segments itin and iltd-ltl/z, inclusive, are made to coincide with the windows 11d-'18, inclusive, in the dielectric sheet. The coil may be formed by using a jig or board having a number of lpins located therein at positions corresponding to the various corners of the coil. In this manner, the wire may be wound about the pins to form the desired 'coil llt?. When formed, the wire coil may be attached to the dielectric material by means of a suitable cementing material or, if desired, the dielectric backing material may be dispensed with and the coil turns bonded together by coating them with lacquer or some suitable plastic coating which, after it dries, serves to bond the turns together.

An alternative way of forming the coil .lll is to print the desired turns pattern onto the sheet of dielectric material by means of any of the various well known printed circuit or printed wiring techniques. This method is a particularly advantageous way of forming the coil as it is rapid and produces an accurate coil pattern.

Where a plurality of dellection coils are required to form a complete detlection yoke, it is desirable that alternate coils for such yoke have a slightly modied construction in order that these coils may nest with one another in a most compact manner. Accordingly, it is also desirable to utilize a ladder coil of the form shown in Fil-G. 2. This coil is similar to that of PIG. il in that the coil of FlG. 2 is made up of a continuous wire or conductor pattern which progresses continuously between the inner region represented by the terminal 21 and an outer region represented by the terminal 22;. Also, the turns are arranged so that the coil 2d has a tirst end rung 2da and a pair of side pieces Zlib and 2de which are intermittently bridged by the rung segments d-29h, inclusive, respectively comprising segments of a fraction of the total turns. In this manner, the width of the side pieces Zlib and Str-5c may vary in a progressive manner from one end of the coil to the other. The successive variations in width of, for example the side piece Zlib, are represented by the successively decreasing dimensions W4, W5 and W6. This may be accomplished by displacing each turn having a rung segment toward the outer region of the coil so as to maintain a substantially equal spacing of all turns from that region. As before, this coil pattern may be printed on a dielectric sheet 23 having windows or panels 2st-2&3, inclusive, cut therein. The coil pattern Ztl of 2 differs from the pattern of FlG. 1 in that the vvariation in width of the side pieces llb and 2de is produced by maintaining the position or the outer edge of such side pieces constant while varying the positions `of successive portions forming the inner edges.

Magnetic deflection coils in accordance with the present invention are constructed from the flat coils of FIGS. il and 2 by rolling7 up each flat coil about one end thereof into a spiral so as to form a rolled ladder coil. Considering, for example, the tlat coil l@ of `FIG. l, this coil may be rolled up about the end lila as indicated by the arrow. ln this manner, the two side pieces llb and lilo form two distinct cylindrical coils and all rung sections overlay each other and form one compact group interconnecting the symmetrical coils. This rolled up coil pattern is shown in FIG. `El ot the drawings, wherein the rolled forms of coils l@ and Ztl of FIGS. l and 2 are indicated by the primary designations llt) and 26 with various attached suffixes. As there indicated, the side pieces tlb and ltlc of the flat coil of FlG. l become the correspondingly designated cylindrical coils ltlb and 10c of FIG. 3. FlG. 3 also shows the two distinct cylindrical coils Zlib and Ztlc and the stack of rung segments which are formed when the coil pattern 2,6 of FIG. 2 is rolled up about, for example, the end 20h thereof. As is apparent from Fl-G. 3, the term cylindrical is not to be limited to the case of a right circular cylinder because, as shown by the coils 1ldb, ille, 2tlb and 20c of FIG. 3, the distinct cylindrical coils may be of rectangular crosssection.

lt will be noted that the variation in the number of turns included in the side pieces of the llat patterns of FlGS. 1 and 2 has produced a nonuniform distribution or density of the turns in each of the resulting rolled ladder coils lll and of FIG. This nonuniform distribution is indicated by the stepped nature or" these coils, the outer criphery of each of the distinct cylindrical coils lllb and lille of rolled ladder coil lll and the inner periphery of each of the distinct cylindrical Coils 2% and 2de of the rolled ladder coil 2d progressively increasing along the length of each coil going toward the stacked rung segments. This distribution of coil turns may be made to follow a desired pattern so as to compensate for delicotion field distortion lthat `would otherwise result, by suitably selecting the number of turns that are to be included in each rung thereof. lt ywill be noted in this regard that the number of turns and rungs shown in the drawings of FIG. jl and FIG. 2 are intended as representative only, as the actual numer of either which may be used may be many times that illustrated.

As indicated by the dimensions Dl-D5, inclusive, of FIG. l, it is necessary that the dimensions of the windows or" flat coil 1li parallel to the side pieces 10b and ltlc either increase or decrease, as the case may be, from one rung to the next in order to make up for the increased circumference which must be covered by these successive sections when the coil pattern is rolled up. This same dimensional variation also applies to the coil pattern Ztl ot FIG. 2.

Referring now to FIGS. 4 and 5 of the drawings, there is shown a representative form of magnetic deflection yoke which may be made by practicing the teachings of the present invention. By way of illustration, a type of magnetic deflection yoke suitable for use with a cathoderay tube is shown and, to this end, a portion 55' of the neck of such a cathode-ray tube is indicated in phantom,

that is, in dash-line form, in order to indicate the position of the deection yoke relative to the cathode-ray tube. Four pairs of interconnected cylindrical coils (four individual rolled ladder coils) of the type described i-n connection with FlG. 3 are required to make up the complete dellection yoke. ln order to properly nest, the outer peripheries of the coils of two or these pairs, the inner peripheries of the coils of the remaining two pairs must continually increase along the lengths of the coils going toward the stacked rung sections. The increasing outer periphery type of rolled ladder coil may be formed by rolling ladder coil lil of FlG. l about its end lila a described or by rolling ladder coil 2li of FrG. 2 about its end 2da. Similarly, the decreasing inner peripherv type ot rolled ladder coil may be formed by rolling ladder coil 2d about its end Ztl/z or by rolling ladder coil l0 about its end llf'z. Of course, if either coil l@ or coil 2li is to be rolled about its end dit or Zilla, respectively, the

widths of the side pieces would have to increase toward ends 10a or 20a rather than as shown in FIGS. l and 2. In FIGS. 4 and 5 two of the rolled ladder coils, the various parts of which are indicated by primary designations liti and 30 with various attached sutiixes, have been formed by rolling up two ladder coils of the type shown in FIG. l and two additional rolled ladder coils, the parts of which are indicated by designations 20 and 40 with various attached suffixes, have been formed by rolling up two ladder coils of the type shown in FIG. 2. These rolled ladder coils are positioned on a ferromag netic core 5t) in an overlapping manner with the smallest outer peripheral portion of each distinct cylindrical coil of the rolled ladder coils of increasing outer periphery positioned adjacent the smallest inner peripheral portion of the overlapping distinct cylindrical coils of the rolled ladder coils of increasing inner periphery. This overlapping is best seen in the cross-sectional view of FIG. 5 which is a view taken on the section line A-A of FIG. 4.

As indicated in the drawings, the ferromagnetic core Sti is of the ring type, that is, of a type which completely encircles or rings the neck portion 55 of the cathode-ray tube. Each of the rolled ladder coils is positioned on the core 50 so that the turns making up each cylindrical coil thereof encircle the core. In order to obtain the preformed rolled ladder coils on the core 50, it is necessary that the core Sii be made of at least two segments or parts which may be separated from one another.

The manner in which the distinct cylindrical coils should be inserted into one another so as to produce the desired compact overlapping is shown by the phantom coil c of FIG. 3 which represents the coil 10c in an altered position. The coil liic is inserted into the coil h so that the outside steps on the cylindrical coil 10c may be neatly .nested in the inner steps of the cylindrical coil Zlib. The results of this overlapping when these coils are positioned on the core 50 are shown in FIG. 5, the coil 10c there being referred to as lltic. The remainder of the rolled ladder coils are similarly positioned on the core 50 in this same overlapping manner. Thus is seen the reason for making two of the rolled ladder coils of the male type and the other two of the Yfemale type.

As is apparent from FIG. 5, the portions of each of the cylindrical coils which are located inside the core Sti fit neatly together with very little unused space remaining, whereas the portions of the coils which are located outside of the core 5t) do not fit together quite so neatly. In this regard, it should be remembered that it is only the coil portions located inside the core Sil which are active in deflecting the electron beam produced by the cathoderay tube 55. This is because the outer coil portions are shielded from the electron beam by the ferromagnetic core 50. Thus, it will be recognized that the locations of the coil portions which are outside the core 50 are not critical as far as deflection of the electron beam is concerned. As is indicated in FIG. 4, the positions of the compact groups of rung sections indicated by the numbers 10a, 20a and 30a are chosen so as not to conflict with one another.

In order to obtain all of the rolled ladder coils on the core 50 in the indicated overlapping manner, it is preferable that at least two of the compact groups of rung sections, for example, the groups having the outer rung sections designated by the numbers 20a and itia, be made extra long in length so that after all four of the rolled ladder coils have been properly inserted into one another there is enough room left over so that the pieces of the core 50 may be inserted within the overlapped coils. After the individual rolled ladder coils have been overlapped and the core pieces inserted into the center regions thereof, the yoke structure may then be suitably clamped together in a rigid manner, for example, by tightening a metallic band or strap around the circumference of the entire yoke structure.

A typical way of interconnecting the coil pairs for actual operation in deiiecting the electron beam is indicated by the symbolic diagram of FIG. 6. This diagram is intended to be purely sy'mbolic and is not intended to represent either the actual or equivalent circuit of the defiection yoke but, nevertheless, serves to enable one to readily understand how the yoke operates. More particularly, the symbolic coil portions 10b, 10c, 30h, and 30e of FIG. 6, correspond to the correspondingly designated portions of the coils of FIG. 5, which are located inside the core 50. The remainder of the coil wiring of FIG. 6 represents that portion of the coil wiring of FIG. 5 which is located outside of the core 50. In this manner, from FIG. 6, it may be seen that the coil portions 10b, 10c, 30h and 36C produce a pair of seriesadding magnetic fields which serve to produce a vertical component of magnetic fiux which is indicated by the dashed lines 57. This component of flux causes the electron beam to be defiected in a horizontal direction. Where, for example, the cathode-ray tube S5 is used in a television receiver, the terminals 60 and 61 of the coil pairs indicated in FIG. 6 are connected to suitable supply circuits of the television receiver for enabling suitable defiection currents to be supplied to these windings. In a similar manner, though not shown in FIG. 6, it 'may be seen that the coil portions 2Gb, 20c, 4Gb and 40C which are located inside of the core 50l may be connected and supplied with suitable deflection currents for producing a horizontal magnetic field, the flux lines of which are represented by the dashed lines 58 of FIG. 5. In this manner, the deflection yoke of FIG. 5 may, for example, be used in a television receiver to produce the desired scanning raster of the electron beam. Of course, where desired, only the coils necessary for deflecting the electron beam in one direction need be included in the yoke structure if deflection in one direction is all that is required of such a yoke structure.

' From the foregoing description of the various portions of the invention, it will be apparent that the ladder coils of FIGS. 1 and 2 are such that highly' accurate deflection coils and deflection yokes may be produced by the use thereof. More particularly, such ladder coils readily lend themselves to printed circuit techniques thus rendering construction of such deflection coils and defiection yokes rapid and economical. Also, by permitting the coil portions located inside the core to be neatly and compactfly overlapped, the construction of deflection coils and yokes in accordance with the present invention, results in increased linearity of the resultant deflection fields, increased power efiiciency, and reduced distributed capacitance.

While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and it is, therefore, aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A rolled ladder coil suitable for use in a cathode-ray tube deiiection yoke comprising:

two distinct cylindrical coils;

and interconnectingr rung sections which overlay each other when rolled, forming one compact group interconnecting said two cylindrical coils.

2. A rolled ladder coil in accordance with claim l, wherein the outer periphery of the two distinct cylindrical coils progressively' increases in the direction of the group of rung sections.

3. A rolled ladder coil in accordance with claim l, wherein the inner periphery of the two distinct cylindrical coils progressively increases in the direction of the group of rung sections.

4. A magnetic deflection yoke for a cathode-ray tube comprising a ring core having mounted thereon a plu- .rality of rolled ladder coils in accordance with claim 1;

each of the rolled ladder coils being positioned on said vcore so that the turns making up each cylindrical coil cilitate coil mounting.

5. A magnetic deection yoke for a cathode-ray tube comprising a ring core having mounted thereon in nested relationship, a plurality of rolled ladder coils in accordance with claim l; each of the rolled ladder coils being positioned on said core s0 that the turns making up each cylindrical coil thereof encircle the core and the core being made up of at least two segments which may be separated to facilitate coil mounting.

References Cited in the file of this patent UNITED STATES PATENTS 2,817,782 over et a1. Dec. 24, 1957 2,830,212 Hanlet Apr. 8, 1958 2,831,135 Hamlet Apr. 15, 1958 2,831,136 Hamlet Apr. 15, 1958 10 3,007,087 Corpew oct. 31, 19611 

1. A ROLLED LADDER COIL SUITABLE FOR USE IN A CATHODE-RAY TUBE DEFLECTION YOKE COMPRISING: TWO DISTINCT CYLINDRICAL COILS; AND INTERCONNECTING RUNG SECTIONS WHICH OVERLAY EACH 